I remember trying to Beyer gel pads once (I think at the local Long & McQuades ages ago). It's a bit of an odd feeling, and slightly claustrophobic. I'm not entirely sure if the pad is a single material, or if it's a gel inside a soft rubbery/silicon shell. Either way: it seals very well, almost sticky feeling, definitely hotter/sweatier, and definitely improves isolation.
If you're curious how it feels, try this: mix a small batch of 1 tbsp gelatin and 1.5 tbsp milk in a small glass bowl, microwave for about 10-15 seconds, let it sit for an hour or two until it congeals. Slap that on your face. It's not sticky or slimy per se, but the texture will make it adhere. (For those curious, this is a home-made face mask for pore cleansing that actually works quite well. Spread a thin-ish layer on your face while still warm, wait 20 minutes for it to dry until you can't move your face and it feels like the mask will explode (trust me, you'll know), then peel it off)
Of interest, Comply also seems to have an earpad in the works... http://www.complyfoam.com/new-comply-premium-headphone-pads/